1. Field of the Invention
The present invention relates to clamping devices and rotary table apparatuses.
2. Description of the Related Art
Rotary table apparatuses used in machine tools or the like are already well known. Such rotary table apparatuses include a driven shaft that is rotationally driven by a driving section such as a motor, and a rotary table that is rotationally driven by this driven shaft and that holds a workpiece or the like. When the driven shaft is driven by the driving section, the driven shaft rotates, the rotational driving force of the driven shaft is transmitted to the rotary table, and the rotary table rotates around its rotation axis.
Such a rotary table apparatus further includes a clamping device for clamping the driven shaft, in order to realize such a function as to securely keep the rotary table still. When the driven shaft has been halted and the rotary table has been positioned, this clamping device clamps the driven shaft to, for example, perform work on the workpiece that is held by the rotary table. Thus, the rotary table can be reliably held still, and work can be performed on the workpiece with high precision. (See, for example, JP 2002-126958A).
The driven shaft is supported rotatably with respect to the housing by bearings or the like. There is, however, a possibility that misalignments may occur in the driven shaft. Examples of such misalignments are axial displacements in which the axis of the driven shaft is displaced from the desired axis, and angular inclinations in which the axial orientation of the driven shaft is inclined from the desired axial orientation. In these cases, there is a discrepancy between the relative positions of the driven shaft and the clamping device. Such a discrepancy in the relative positions may also occur when there are misalignments due to displacement or inclination of the clamping device, even when there is no misalignment of the driven shaft.
Consequently, there is a need for a clamping device that can properly clamp the driven shaft even in such a situation.